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Fixed #10506, #13793, #14891, #25201 -- Introduced new APIs to specify models' default and base managers. 

This deprecates use_for_related_fields.

Old API:

class CustomManager(models.Model):
    use_for_related_fields = True

class Model(models.Model):
    custom_manager = CustomManager()

New API:

class Model(models.Model):
    custom_manager = CustomManager()

    class Meta:
        base_manager_name = 'custom_manager'

Refs #20932, #25897.

Thanks Carl Meyer for the guidance throughout this work.
Thanks Tim Graham for writing the docs.
This commit is contained in:
Loïc Bistuer 2016-04-17 18:55:55 +07:00
parent 3a47d42fa3
commit ed0ff913c6
18 changed files with 815 additions and 226 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
django/contrib/gis/db/models/manager.py
View File

@ -13,6 +13,10 @@ class GeoManager(Manager.from_queryset(GeoQuerySet)):
# properly.
use_for_related_fields = True
# No need to bother users with the use_for_related_fields
# deprecation for this manager which is itself deprecated.
silence_use_for_related_fields_deprecation = True
def __init__(self, *args, **kwargs):
warnings.warn(
"The GeoManager class is deprecated. Simply use a normal manager "

58
django/db/migrations/state.py
View File

@ -476,47 +476,29 @@ class ModelState(object):
if not any((isinstance(base, six.string_types) or issubclass(base, models.Model)) for base in bases):
bases = (models.Model,)
# Constructs all managers on the model
managers_mapping = {}
managers = []
def reconstruct_manager(mgr):
as_manager, manager_path, qs_path, args, kwargs = mgr.deconstruct()
if as_manager:
qs_class = import_string(qs_path)
instance = qs_class.as_manager()
else:
manager_class = import_string(manager_path)
instance = manager_class(*args, **kwargs)
# We rely on the ordering of the creation_counter of the original
# instance
name = force_text(mgr.name)
managers_mapping[name] = (mgr.creation_counter, instance)
if hasattr(model, "_default_manager"):
default_manager_name = force_text(model._default_manager.name)
# Make sure the default manager is always the first
# Make sure the default manager is always first since ordering chooses
# the default manager.
if not model._default_manager.auto_created:
if model._default_manager.use_in_migrations:
reconstruct_manager(model._default_manager)
default_manager = copy.copy(model._default_manager)
default_manager._set_creation_counter()
# If the default manager doesn't have `use_in_migrations = True`,
# shim a default manager so another manager isn't promoted in its
# place.
else:
# Force this manager to be the first and thus default
managers_mapping[default_manager_name] = (0, models.Manager())
for manager in model._meta.managers:
if manager.name == "_base_manager" or not manager.use_in_migrations:
continue
reconstruct_manager(manager)
# Sort all managers by their creation counter but take only name and
# instance for further processing
managers = [
(name, instance) for name, (cc, instance) in
sorted(managers_mapping.items(), key=lambda v: v[1])
]
# If the only manager on the model is the default manager defined
# by Django (`objects = models.Manager()`), this manager will not
# be added to the model state.
if managers == [('objects', models.Manager())]:
managers = []
else:
managers = []
default_manager = models.Manager()
default_manager.model = model
default_manager.name = model._default_manager.name
managers.append((force_text(default_manager.name), default_manager))
for manager in model._meta.managers:
if manager.use_in_migrations and manager is not model._default_manager:
manager = copy.copy(manager)
manager._set_creation_counter()
managers.append((force_text(manager.name), manager))
# Construct the new ModelState
return cls(

98
django/db/models/base.py
View File

@ -24,11 +24,12 @@ from django.db.models.fields.related import (
ForeignObjectRel, ManyToOneRel, OneToOneField, lazy_related_operation,
resolve_relation,
)
from django.db.models.manager import ensure_default_manager
from django.db.models.manager import Manager
from django.db.models.options import Options
from django.db.models.query import Q
from django.db.models.utils import make_model_tuple
from django.utils import six
from django.utils.deprecation import RemovedInDjango20Warning
from django.utils.encoding import (
force_str, force_text, python_2_unicode_compatible,
)
@ -345,10 +346,99 @@ class ModelBase(type):
if get_absolute_url_override:
setattr(cls, 'get_absolute_url', get_absolute_url_override)
ensure_default_manager(cls)
if not opts.managers or cls._requires_legacy_default_manager():
if any(f.name == 'objects' for f in opts.fields):
raise ValueError(
"Model %s must specify a custom Manager, because it has a "
"field named 'objects'." % cls.__name__
)
manager = Manager()
manager.auto_created = True
cls.add_to_class('objects', manager)
signals.class_prepared.send(sender=cls)
def _requires_legacy_default_manager(cls): # RemovedInDjango20Warning
opts = cls._meta
if opts.manager_inheritance_from_future:
return False
future_default_manager = opts.default_manager
# Step 1: Locate a manager that would have been promoted
# to default manager with the legacy system.
for manager in opts.managers:
originating_model = manager._originating_model
if (cls is originating_model or cls._meta.proxy or
originating_model._meta.abstract):
if manager is not cls._default_manager and not opts.default_manager_name:
warnings.warn(
"Managers from concrete parents will soon qualify as default "
"managers if they appear before any other managers in the "
"MRO. As a result, '{legacy_default_manager}' declared on "
"'{legacy_default_manager_model}' will no longer be the "
"default manager for '{model}' in favor of "
"'{future_default_manager}' declared on "
"'{future_default_manager_model}'. "
"You can redeclare '{legacy_default_manager}' on '{cls}' "
"to keep things the way they are or you can switch to the new "
"behavior right away by setting "
"`Meta.manager_inheritance_from_future` to `True`.".format(
cls=cls.__name__,
model=opts.label,
legacy_default_manager=manager.name,
legacy_default_manager_model=manager._originating_model._meta.label,
future_default_manager=future_default_manager.name,
future_default_manager_model=future_default_manager._originating_model._meta.label,
),
RemovedInDjango20Warning, 2
)
opts.default_manager_name = manager.name
opts._expire_cache()
break
# Step 2: Since there are managers but none of them qualified as
# default managers under the legacy system (meaning that there are
# managers from concrete parents that would be promoted under the
# new system), we need to create a new Manager instance for the
# 'objects' attribute as a deprecation shim.
else:
# If the "future" default manager was auto created there is no
# point warning the user since it's basically the same manager.
if not future_default_manager.auto_created:
warnings.warn(
"Managers from concrete parents will soon qualify as "
"default managers. As a result, the 'objects' manager "
"won't be created (or recreated) automatically "
"anymore on '{model}' and '{future_default_manager}' "
"declared on '{future_default_manager_model}' will be "
"promoted to default manager. You can declare "
"explicitly `objects = models.Manager()` on '{cls}' "
"to keep things the way they are or you can switch "
"to the new behavior right away by setting "
"`Meta.manager_inheritance_from_future` to `True`.".format(
cls=cls.__name__,
model=opts.label,
future_default_manager=future_default_manager.name,
future_default_manager_model=future_default_manager._originating_model._meta.label,
),
RemovedInDjango20Warning, 2
)
return True
@property
def _base_manager(cls):
return cls._meta.base_manager
@property
def _default_manager(cls):
return cls._meta.default_manager
class ModelState(object):
"""
@ -896,8 +986,8 @@ class Model(six.with_metaclass(ModelBase)):
order = '_order' if is_next else '-_order'
order_field = self._meta.order_with_respect_to
filter_args = order_field.get_filter_kwargs_for_object(self)
obj = self._default_manager.filter(**filter_args).filter(**{
'_order__%s' % op: self._default_manager.values('_order').filter(**{
obj = self.__class__._default_manager.filter(**filter_args).filter(**{
'_order__%s' % op: self.__class__._default_manager.values('_order').filter(**{
self._meta.pk.name: self.pk
})
}).order_by(order)[:1].get()

47
django/db/models/fields/related_descriptors.py
View File

@ -104,11 +104,20 @@ class ForwardManyToOneDescriptor(object):
return hasattr(instance, self.cache_name)
def get_queryset(self, **hints):
manager = self.field.remote_field.model._default_manager
# If the related manager indicates that it should be used for
# related fields, respect that.
if not getattr(manager, 'use_for_related_fields', False):
manager = self.field.remote_field.model._base_manager
related_model = self.field.remote_field.model
if (not related_model._meta.base_manager_name and
getattr(related_model._default_manager, 'use_for_related_fields', False)):
if not getattr(related_model._default_manager, 'silence_use_for_related_fields_deprecation', False):
warnings.warn(
"use_for_related_fields is deprecated, instead "
"set Meta.base_manager_name on '{}'.".format(related_model._meta.label),
RemovedInDjango20Warning, 2
)
manager = related_model._default_manager
else:
manager = related_model._base_manager
return manager.db_manager(hints=hints).all()
def get_prefetch_queryset(self, instances, queryset=None):
@ -281,11 +290,20 @@ class ReverseOneToOneDescriptor(object):
return hasattr(instance, self.cache_name)
def get_queryset(self, **hints):
manager = self.related.related_model._default_manager
# If the related manager indicates that it should be used for
# related fields, respect that.
if not getattr(manager, 'use_for_related_fields', False):
manager = self.related.related_model._base_manager
related_model = self.related.related_model
if (not related_model._meta.base_manager_name and
getattr(related_model._default_manager, 'use_for_related_fields', False)):
if not getattr(related_model._default_manager, 'silence_use_for_related_fields_deprecation', False):
warnings.warn(
"use_for_related_fields is deprecated, instead "
"set Meta.base_manager_name on '{}'.".format(related_model._meta.label),
RemovedInDjango20Warning, 2
)
manager = related_model._default_manager
else:
manager = related_model._base_manager
return manager.db_manager(hints=hints).all()
def get_prefetch_queryset(self, instances, queryset=None):
@ -437,8 +455,10 @@ class ReverseManyToOneDescriptor(object):
@cached_property
def related_manager_cls(self):
related_model = self.rel.related_model
return create_reverse_many_to_one_manager(
self.rel.related_model._default_manager.__class__,
related_model._default_manager.__class__,
self.rel,
)
@ -697,9 +717,10 @@ class ManyToManyDescriptor(ReverseManyToOneDescriptor):
@cached_property
def related_manager_cls(self):
model = self.rel.related_model if self.reverse else self.rel.model
related_model = self.rel.related_model if self.reverse else self.rel.model
return create_forward_many_to_many_manager(
model._default_manager.__class__,
related_model._default_manager.__class__,
self.rel,
reverse=self.reverse,
)

39
django/db/models/manager.py
View File

@ -8,47 +8,14 @@ from django.utils import six
from django.utils.encoding import python_2_unicode_compatible
def can_use_for_related_field(manager_class):
return manager_class is Manager or getattr(manager_class, 'use_for_related_fields', False)
def ensure_default_manager(model):
"""
Ensures that a Model subclass contains a default manager and sets the
_default_manager and _base_manager attributes on the class.
"""
if not model._meta.managers:
if any(f.name == 'objects' for f in model._meta.fields):
raise ValueError(
"Model %s must specify a custom Manager, because it has a "
"field named 'objects'" % model.__name__
)
model.add_to_class('objects', Manager())
model._default_manager = model._meta.managers[0]
# Just alias _base_manager if default manager is suitable.
if can_use_for_related_field(model._default_manager.__class__):
model._base_manager = model._default_manager
# Otherwise search for a suitable manager type in the default manager MRO.
else:
for base_manager_class in model._default_manager.__class__.mro()[1:]:
if can_use_for_related_field(base_manager_class):
model._base_manager = base_manager_class()
model._base_manager.name = '_base_manager'
model._base_manager.model = model
break
else:
raise ValueError("Could not find a suitable base manager.")
@python_2_unicode_compatible
class BaseManager(object):
# Tracks each time a Manager instance is created. Used to retain order.
creation_counter = 0
# Set to True for the 'objects' managers that are automatically created.
auto_created = False
#: If set to True the manager will be serialized into migrations and will
#: thus be available in e.g. RunPython operations
use_in_migrations = False

90
django/db/models/options.py
View File

@ -10,6 +10,7 @@ from django.apps import apps
from django.conf import settings
from django.core.exceptions import FieldDoesNotExist
from django.db import connections
from django.db.models import Manager
from django.db.models.fields import AutoField
from django.db.models.fields.proxy import OrderWrt
from django.utils import six
@ -41,7 +42,8 @@ DEFAULT_NAMES = (
'app_label', 'db_tablespace', 'abstract', 'managed', 'proxy', 'swappable',
'auto_created', 'index_together', 'apps', 'default_permissions',
'select_on_save', 'default_related_name', 'required_db_features',
'required_db_vendor',
'required_db_vendor', 'base_manager_name', 'default_manager_name',
'manager_inheritance_from_future',
)
@ -73,9 +75,11 @@ def make_immutable_fields_list(name, data):
@python_2_unicode_compatible
class Options(object):
FORWARD_PROPERTIES = {'fields', 'many_to_many', 'concrete_fields',
'local_concrete_fields', '_forward_fields_map',
'managers', 'managers_map'}
FORWARD_PROPERTIES = {
'fields', 'many_to_many', 'concrete_fields', 'local_concrete_fields',
'_forward_fields_map', 'managers', 'managers_map', 'base_manager',
'default_manager',
}
REVERSE_PROPERTIES = {'related_objects', 'fields_map', '_relation_tree'}
default_apps = apps
@ -85,7 +89,10 @@ class Options(object):
self.local_fields = []
self.local_many_to_many = []
self.private_fields = []
self.manager_inheritance_from_future = False
self.local_managers = []
self.base_manager_name = None
self.default_manager_name = None
self.model_name = None
self.verbose_name = None
self.verbose_name_plural = None
@ -368,6 +375,10 @@ class Options(object):
manager.model = self.model
managers.append((depth, manager.creation_counter, manager))
# Used for deprecation of legacy manager inheritance,
# remove afterwards. (RemovedInDjango20Warning)
manager._originating_model = base
return make_immutable_fields_list(
"managers",
(m[2] for m in sorted(managers)),
@ -377,6 +388,77 @@ class Options(object):
def managers_map(self):
return {manager.name: manager for manager in reversed(self.managers)}
@cached_property
def base_manager(self):
base_manager_name = self.base_manager_name
if not base_manager_name:
# Get the first parent's base_manager_name if there's one.
for parent in self.model.mro()[1:]:
if hasattr(parent, '_meta'):
if parent._base_manager.name != '_base_manager':
base_manager_name = parent._base_manager.name
break
if base_manager_name:
try:
return self.managers_map[base_manager_name]
except KeyError:
raise ValueError(
"%s has no manager named %r" % (
self.object_name,
base_manager_name,
)
)
# Deprecation shim for `use_for_related_fields`.
for i, base_manager_class in enumerate(self.default_manager.__class__.mro()):
if getattr(base_manager_class, 'use_for_related_fields', False):
if not getattr(base_manager_class, 'silence_use_for_related_fields_deprecation', False):
warnings.warn(
"use_for_related_fields is deprecated, instead "
"set Meta.base_manager_name on '{}'.".format(self.model._meta.label),
RemovedInDjango20Warning, 2
)
if i == 0:
manager = self.default_manager
else:
manager = base_manager_class()
manager.name = '_base_manager'
manager.model = self.model
return manager
manager = Manager()
manager.name = '_base_manager'
manager.model = self.model
manager.auto_created = True
return manager
@cached_property
def default_manager(self):
default_manager_name = self.default_manager_name
if not default_manager_name and not self.local_managers:
# Get the first parent's default_manager_name if there's one.
for parent in self.model.mro()[1:]:
if hasattr(parent, '_meta'):
default_manager_name = parent._meta.default_manager_name
break
if default_manager_name:
try:
return self.managers_map[default_manager_name]
except KeyError:
raise ValueError(
"%s has no manager named %r" % (
self.object_name,
default_manager_name,
)
)
if self.managers:
return self.managers[0]
@cached_property
def fields(self):
"""

6
docs/internals/deprecation.txt
View File

@ -175,6 +175,12 @@ details on these changes.
* The ``escape`` filter will change to use
``django.utils.html.conditional_escape()``.
* ``Manager.use_for_related_fields`` will be removed.
* Model ``Manager`` inheritance will follow MRO inheritance rules and the
``Meta.manager_inheritance_from_future`` to opt-in to this behavior will be
removed.
.. _deprecation-removed-in-1.10:
1.10

20
docs/ref/models/options.txt
View File

@ -35,6 +35,16 @@ Available ``Meta`` options
or ``app_label.model_name`` you can use ``model._meta.label``
or ``model._meta.label_lower`` respectively.
``base_manager_name``
---------------------
.. attribute:: Options.base_manager_name
.. versionadded:: 1.10
The name of the manager to use for the model's
:attr:`~django.db.models.Model._base_manager`.
``db_table``
------------
@ -95,6 +105,16 @@ Django quotes column and table names behind the scenes.
setting, if set. If the backend doesn't support tablespaces, this option is
ignored.
``default_manager_name``
------------------------
.. attribute:: Options.default_manager_name
.. versionadded:: 1.10
The name of the manager to use for the model's
:attr:`~django.db.models.Model._default_manager`.
``default_related_name``
------------------------

23
docs/releases/1.10.txt
View File

@ -432,6 +432,13 @@ Models
* ``Model.__init__()`` now sets values of virtual fields from its keyword
arguments.
* The new :attr:`Meta.base_manager_name
<django.db.models.Options.base_manager_name>` and
:attr:`Meta.default_manager_name
<django.db.models.Options.default_manager_name>` options allow controlling
the :attr:`~django.db.models.Model._base_manager` and
:attr:`~django.db.models.Model._default_manager`, respectively.
Requests and Responses
~~~~~~~~~~~~~~~~~~~~~~
@ -1063,6 +1070,22 @@ always be applied as the last filter no matter where in the filter chain it
appeared) is deprecated. The filter will change to immediately apply
:func:`~django.utils.html.conditional_escape` in Django 2.0.
``Manager.use_for_related_fields`` and inheritance changes
----------------------------------------------------------
``Manager.use_for_related_fields`` is deprecated in favor of setting
:attr:`Meta.base_manager_name <django.db.models.Options.base_manager_name>` on
the model.
Model ``Manager`` inheritance will follow MRO inheritance rules in Django 2.0,
changing the current behavior where managers defined on non-abstract base
classes aren't inherited by child classes. A deprecating warning with
instructions on how to adapt your code is raised if you have any affected
managers. You'll either redeclare a manager from an abstract model on the child
class to override the manager from the concrete model, or you'll set the
model's ``Meta.manager_inheritance_from_future=True`` option to opt-in to the
new inheritance behavior.
Miscellaneous
-------------

172
docs/topics/db/managers.txt
View File

@ -172,35 +172,59 @@ and ``Person.people.all()``, yielding predictable results.
.. _default-managers:
Default managers
~~~~~~~~~~~~~~~~
----------------
.. attribute:: Model._default_manager
If you use custom ``Manager`` objects, take note that the first ``Manager``
Django encounters (in the order in which they're defined in the model) has a
special status. Django interprets the first ``Manager`` defined in a class as
the "default" ``Manager``, and several parts of Django
(including :djadmin:`dumpdata`) will use that ``Manager``
exclusively for that model. As a result, it's a good idea to be careful in
your choice of default manager in order to avoid a situation where overriding
``get_queryset()`` results in an inability to retrieve objects you'd like to
work with.
the "default" ``Manager``, and several parts of Django (including
:djadmin:`dumpdata`) will use that ``Manager`` exclusively for that model. As a
result, it's a good idea to be careful in your choice of default manager in
order to avoid a situation where overriding ``get_queryset()`` results in an
inability to retrieve objects you'd like to work with.
You can specify a custom default manager using :attr:`Meta.base_manager_name
<django.db.models.Options.base_manager_name>`.
If you're writing some code that must handle an unknown model, for example, in
a third-party app that implements a generic view, use this manager (or
:attr:`~Model._base_manager`) rather than assuming the model has an ``objects``
manager.
Base managers
-------------
.. attribute:: Model._base_manager
.. _managers-for-related-objects:
Using managers for related object access
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
By default, Django uses an instance of a "plain" manager class when accessing
related objects (i.e. ``choice.poll``), not the default manager on the related
object. This is because Django needs to be able to retrieve the related
object, even if it would otherwise be filtered out (and hence be inaccessible)
by the default manager.
By default, Django uses an instance of the ``Model._base_manager`` manager
class when accessing related objects (i.e. ``choice.poll``), not the
``_default_manager`` on the related object. This is because Django needs to be
able to retrieve the related object, even if it would otherwise be filtered out
(and hence be inaccessible) by the default manager.
If the normal plain manager class (:class:`django.db.models.Manager`) is not
appropriate for your circumstances, you can force Django to use the same class
as the default manager for your model by setting the ``use_for_related_fields``
attribute on the manager class. This is documented fully below_.
If the normal base manager class (:class:`django.db.models.Manager`) isn't
appropriate for your circumstances, you can tell Django which class to use by
setting :attr:`Meta.base_manager_name
<django.db.models.Options.base_manager_name>`.
.. _below: manager-types_
Don't filter away any results in this type of manager subclass
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This manager is used to access objects that are related to from some other
model. In those situations, Django has to be able to see all the objects for
the model it is fetching, so that *anything* which is referred to can be
retrieved.
If you override the ``get_queryset()`` method and filter out any rows, Django
will return incorrect results. Don't do that. A manager that filters results
in ``get_queryset()`` is not appropriate for use as a default manager.
.. _calling-custom-queryset-methods-from-manager:
@ -321,19 +345,21 @@ You may also store the generated class into a variable::
Custom managers and model inheritance
-------------------------------------
Here's how Django handles custom managers and
:ref:`model inheritance <model-inheritance>`:
Here's how Django handles custom managers and :ref:`model inheritance
<model-inheritance>`:
1. Managers from base classes are always inherited by the child class,
#. Managers from base classes are always inherited by the child class,
using Python's normal name resolution order (names on the child
class override all others; then come names on the first parent class,
and so on).
2. The default manager on a class is either the first manager declared on the
class, if that exists, or the default manager of the first parent class in
the parent hierarchy, if that exists. If no manager is explicitly declared,
Django automatically creates the `objects` manager and it becomes the default
manager.
#. If no managers are declared on a model and/or its parents, Django
automatically creates the ``objects`` manager.
#. The default manager on a class is either the one chosen with
:attr:`Meta.default_manager_name
<django.db.models.Options.default_manager_name>`, or the first manager
declared on the model, or the default manager of the first parent model.
.. versionchanged:: 1.10
@ -428,99 +454,3 @@ However, if you're overriding ``__getattr__`` or some other private
method of your ``Manager`` object that controls object state, you
should ensure that you don't affect the ability of your ``Manager`` to
be copied.
.. _manager-types:
Controlling automatic manager types
===================================
This document has already mentioned a couple of places where Django creates a
manager class for you: `default managers`_ and the "plain" manager used to
`access related objects`_. There are other places in the implementation of
Django where temporary plain managers are needed. Those automatically created
managers will normally be instances of the :class:`django.db.models.Manager`
class.
.. _default managers: manager-names_
.. _access related objects: managers-for-related-objects_
Throughout this section, we will use the term "automatic manager" to mean a
manager that Django creates for you -- either as a default manager on a model
with no managers, or to use temporarily when accessing related objects.
Sometimes this default class won't be the right choice. The default manager
may not have all the methods you need to work with your data. A custom manager
class of your own will allow you to create custom ``QuerySet`` objects to give
you the information you need.
Django provides a way for custom manager developers to say that their manager
class should be used for automatic managers whenever it is the default manager
on a model. This is done by setting the ``use_for_related_fields`` attribute on
the manager class::
class MyManager(models.Manager):
use_for_related_fields = True
# ...
If this attribute is set on the *default* manager for a model (only the
default manager is considered in these situations), Django will use that class
whenever it needs to automatically create a manager for the class. Otherwise,
it will use :class:`django.db.models.Manager`.
.. admonition:: Historical Note
Given the purpose for which it's used, the name of this attribute
(``use_for_related_fields``) might seem a little odd. Originally, the
attribute only controlled the type of manager used for related field
access, which is where the name came from. As it became clear the concept
was more broadly useful, the name hasn't been changed. This is primarily
so that existing code will :doc:`continue to work </misc/api-stability>` in
future Django versions.
Writing correct managers for use in automatic manager instances
---------------------------------------------------------------
The ``use_for_related_fields`` feature is primarily for managers that need to
return a custom ``QuerySet`` subclass. In providing this functionality in your
manager, there are a couple of things to remember.
Do not filter away any results in this type of manager subclass
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
One reason an automatic manager is used is to access objects that are related
to from some other model. In those situations, Django has to be able to see
all the objects for the model it is fetching, so that *anything* which is
referred to can be retrieved.
If you override the ``get_queryset()`` method and filter out any rows, Django
will return incorrect results. Don't do that. A manager that filters results
in ``get_queryset()`` is not appropriate for use as an automatic manager.
Set ``use_for_related_fields`` when you define the class
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ``use_for_related_fields`` attribute must be set on the manager *class*, not
on an *instance* of the class. The earlier example shows the correct way to set
it, whereas the following will not work::
# BAD: Incorrect code
class MyManager(models.Manager):
# ...
pass
# Sets the attribute on an instance of MyManager. Django will
# ignore this setting.
mgr = MyManager()
mgr.use_for_related_fields = True
class MyModel(models.Model):
# ...
objects = mgr
# End of incorrect code.
You also shouldn't change the attribute on the class object after it has been
used in a model, since the attribute's value is processed when the model class
is created and not subsequently reread. Set the attribute on the manager class
when it is first defined, as in the initial example of this section and
everything will work smoothly.

9
tests/basic/tests.py
View File

@ -637,7 +637,7 @@ class SelectOnSaveTests(TestCase):
# test this properly otherwise. Article's manager, because
# proxy models use their parent model's _base_manager.
orig_class = Article._base_manager.__class__
orig_class = Article._base_manager._queryset_class
class FakeQuerySet(QuerySet):
# Make sure the _update method below is in fact called.
@ -648,11 +648,8 @@ class SelectOnSaveTests(TestCase):
super(FakeQuerySet, self)._update(*args, **kwargs)
return 0
class FakeManager(orig_class):
def get_queryset(self):
return FakeQuerySet(self.model)
try:
Article._base_manager.__class__ = FakeManager
Article._base_manager._queryset_class = FakeQuerySet
asos = ArticleSelectOnSave.objects.create(pub_date=datetime.now())
with self.assertNumQueries(3):
asos.save()
@ -665,7 +662,7 @@ class SelectOnSaveTests(TestCase):
with self.assertRaises(DatabaseError):
asos.save(update_fields=['pub_date'])
finally:
Article._base_manager.__class__ = orig_class
Article._base_manager._queryset_class = orig_class
class ModelRefreshTests(TestCase):

12
tests/custom_managers/models.py
View File

@ -172,6 +172,18 @@ class Car(models.Model):
return self.name
class FastCarAsBase(Car):
class Meta:
proxy = True
base_manager_name = 'fast_cars'
class FastCarAsDefault(Car):
class Meta:
proxy = True
default_manager_name = 'fast_cars'
class RestrictedManager(models.Manager):
def get_queryset(self):
return super(RestrictedManager, self).get_queryset().filter(is_public=True)

33
tests/custom_managers/tests.py
View File

@ -6,8 +6,9 @@ from django.utils import six
from .models import (
Book, Car, CustomManager, CustomQuerySet, DeconstructibleCustomManager,
FunPerson, OneToOneRestrictedModel, Person, PersonFromAbstract,
PersonManager, PublishedBookManager, RelatedModel, RestrictedModel,
FastCarAsBase, FastCarAsDefault, FunPerson, OneToOneRestrictedModel,
Person, PersonFromAbstract, PersonManager, PublishedBookManager,
RelatedModel, RestrictedModel,
)
@ -558,6 +559,34 @@ class TestCars(TestCase):
],
lambda c: c.name
)
# explicit default manager
self.assertQuerysetEqual(
FastCarAsDefault.cars.order_by("name"), [
"Corvette",
"Neon",
],
lambda c: c.name
)
self.assertQuerysetEqual(
FastCarAsDefault._default_manager.all(), [
"Corvette",
],
lambda c: c.name
)
# explicit base manager
self.assertQuerysetEqual(
FastCarAsBase.cars.order_by("name"), [
"Corvette",
"Neon",
],
lambda c: c.name
)
self.assertQuerysetEqual(
FastCarAsBase._base_manager.all(), [
"Corvette",
],
lambda c: c.name
)
class CustomManagersRegressTestCase(TestCase):

3
tests/managers_regress/models.py
View File

@ -118,6 +118,9 @@ class Child5(AbstractBase3):
class Child6(Child4):
value = models.IntegerField()
class Meta:
manager_inheritance_from_future = True
class Child7(Parent):
objects = models.Manager()

386
tests/managers_regress/tests.py
View File

@ -1,9 +1,13 @@
from __future__ import unicode_literals
import warnings
from django.db import models
from django.db.utils import DatabaseError
from django.template import Context, Template
from django.test import TestCase, override_settings
from django.test.utils import isolate_apps
from django.utils.deprecation import RemovedInDjango20Warning
from django.utils.encoding import force_text
from .models import (
@ -160,3 +164,385 @@ class ManagersRegressionTests(TestCase):
related = RelatedModel.objects.create(exact=False)
relation = related.test_fk.create()
self.assertEqual(related.test_fk.get(), relation)
@isolate_apps('managers_regress')
class TestManagerInheritance(TestCase):
def test_implicit_inheritance(self):
class CustomManager(models.Manager):
pass
class AbstractModel(models.Model):
custom_manager = CustomManager()
class Meta:
abstract = True
class PlainModel(models.Model):
custom_manager = CustomManager()
self.assertIsInstance(PlainModel._base_manager, models.Manager)
self.assertIsInstance(PlainModel._default_manager, CustomManager)
class ModelWithAbstractParent(AbstractModel):
class Meta:
manager_inheritance_from_future = True
self.assertIsInstance(ModelWithAbstractParent._base_manager, models.Manager)
self.assertIsInstance(ModelWithAbstractParent._default_manager, CustomManager)
class ProxyModel(PlainModel):
class Meta:
manager_inheritance_from_future = True
proxy = True
self.assertIsInstance(ProxyModel._base_manager, models.Manager)
self.assertIsInstance(ProxyModel._default_manager, CustomManager)
class MTIModel(PlainModel):
class Meta:
manager_inheritance_from_future = True
self.assertIsInstance(MTIModel._base_manager, models.Manager)
self.assertIsInstance(MTIModel._default_manager, CustomManager)
def test_default_manager_inheritance(self):
class CustomManager(models.Manager):
pass
class AbstractModel(models.Model):
another_manager = models.Manager()
custom_manager = CustomManager()
class Meta:
default_manager_name = 'custom_manager'
abstract = True
class PlainModel(models.Model):
another_manager = models.Manager()
custom_manager = CustomManager()
class Meta:
default_manager_name = 'custom_manager'
self.assertIsInstance(PlainModel._default_manager, CustomManager)
class ModelWithAbstractParent(AbstractModel):
class Meta:
manager_inheritance_from_future = True
self.assertIsInstance(ModelWithAbstractParent._default_manager, CustomManager)
class ProxyModel(PlainModel):
class Meta:
manager_inheritance_from_future = True
proxy = True
self.assertIsInstance(ProxyModel._default_manager, CustomManager)
class MTIModel(PlainModel):
class Meta:
manager_inheritance_from_future = True
self.assertIsInstance(MTIModel._default_manager, CustomManager)
def test_base_manager_inheritance(self):
class CustomManager(models.Manager):
pass
class AbstractModel(models.Model):
another_manager = models.Manager()
custom_manager = CustomManager()
class Meta:
base_manager_name = 'custom_manager'
abstract = True
class PlainModel(models.Model):
another_manager = models.Manager()
custom_manager = CustomManager()
class Meta:
base_manager_name = 'custom_manager'
self.assertIsInstance(PlainModel._base_manager, CustomManager)
class ModelWithAbstractParent(AbstractModel):
class Meta:
manager_inheritance_from_future = True
self.assertIsInstance(ModelWithAbstractParent._base_manager, CustomManager)
class ProxyModel(PlainModel):
class Meta:
manager_inheritance_from_future = True
proxy = True
self.assertIsInstance(ProxyModel._base_manager, CustomManager)
class MTIModel(PlainModel):
class Meta:
manager_inheritance_from_future = True
self.assertIsInstance(MTIModel._base_manager, CustomManager)
@isolate_apps('managers_regress')
class TestManagerDeprecations(TestCase):
def test_use_for_related_fields_on_geomanager(self):
from django.contrib.gis.db.models import GeoManager
class MyModel(models.Model):
objects = GeoManager()
# Shouldn't issue any warnings, since GeoManager itself will be
# deprecated at the same time as use_for_related_fields, there
# is no point annoying users with this deprecation.
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
MyModel._base_manager
self.assertEqual(len(warns), 0)
def test_use_for_related_fields_for_base_manager(self):
class MyManager(models.Manager):
use_for_related_fields = True
class MyModel(models.Model):
objects = MyManager()
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
MyModel._base_manager
self.assertEqual(len(warns), 1)
self.assertEqual(
str(warns[0].message),
"use_for_related_fields is deprecated, "
"instead set Meta.base_manager_name on "
"'managers_regress.MyModel'.",
)
# With the new base_manager_name API there shouldn't be any warnings.
class MyModel2(models.Model):
objects = MyManager()
class Meta:
base_manager_name = 'objects'
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
MyModel2._base_manager
self.assertEqual(len(warns), 0)
def test_use_for_related_fields_for_many_to_one(self):
class MyManager(models.Manager):
use_for_related_fields = True
class MyRelModel(models.Model):
objects = MyManager()
class MyModel(models.Model):
fk = models.ForeignKey(MyRelModel, on_delete=models.DO_NOTHING)
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
try:
MyModel(fk_id=42).fk
except DatabaseError:
pass
self.assertEqual(len(warns), 1)
self.assertEqual(
str(warns[0].message),
"use_for_related_fields is deprecated, "
"instead set Meta.base_manager_name on "
"'managers_regress.MyRelModel'.",
)
# With the new base_manager_name API there shouldn't be any warnings.
class MyRelModel2(models.Model):
objects = MyManager()
class Meta:
base_manager_name = 'objects'
class MyModel2(models.Model):
fk = models.ForeignKey(MyRelModel2, on_delete=models.DO_NOTHING)
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
try:
MyModel2(fk_id=42).fk
except DatabaseError:
pass
self.assertEqual(len(warns), 0)
def test_use_for_related_fields_for_one_to_one(self):
class MyManager(models.Manager):
use_for_related_fields = True
class MyRelModel(models.Model):
objects = MyManager()
class MyModel(models.Model):
o2o = models.OneToOneField(MyRelModel, on_delete=models.DO_NOTHING)
objects = MyManager()
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
try:
MyModel(o2o_id=42).o2o
except DatabaseError:
pass
self.assertEqual(len(warns), 1)
self.assertEqual(
str(warns[0].message),
"use_for_related_fields is deprecated, "
"instead set Meta.base_manager_name on "
"'managers_regress.MyRelModel'.",
)
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
try:
MyRelModel(pk=42).mymodel
except DatabaseError:
pass
self.assertEqual(len(warns), 1)
self.assertEqual(
str(warns[0].message),
"use_for_related_fields is deprecated, "
"instead set Meta.base_manager_name on "
"'managers_regress.MyModel'.",
)
# With the new base_manager_name API there shouldn't be any warnings.
class MyRelModel2(models.Model):
objects = MyManager()
class Meta:
base_manager_name = 'objects'
class MyModel2(models.Model):
o2o = models.OneToOneField(MyRelModel2, on_delete=models.DO_NOTHING)
objects = MyManager()
class Meta:
base_manager_name = 'objects'
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
try:
MyModel2(o2o_id=42).o2o
except DatabaseError:
pass
try:
MyRelModel2(pk=42).mymodel2
except DatabaseError:
pass
self.assertEqual(len(warns), 0)
def test_legacy_objects_is_created(self):
class ConcreteParentWithoutManager(models.Model):
pass
class ConcreteParentWithManager(models.Model):
default = models.Manager()
class AbstractParent(models.Model):
default = models.Manager()
class Meta:
abstract = True
# Shouldn't complain since the inherited manager
# is basically the same that would have been created.
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
class MyModel(ConcreteParentWithoutManager):
pass
self.assertEqual(len(warns), 0)
# Should create 'objects' (set as default) and warn that
# it will no longer be the case in the future.
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
class MyModel2(ConcreteParentWithManager):
pass
self.assertEqual(len(warns), 1)
self.assertEqual(
str(warns[0].message),
"Managers from concrete parents will soon qualify as default "
"managers. As a result, the 'objects' manager won't be created "
"(or recreated) automatically anymore on "
"'managers_regress.MyModel2' and 'default' declared on "
"'managers_regress.ConcreteParentWithManager' will be promoted "
"to default manager. You can declare explicitly "
"`objects = models.Manager()` on 'MyModel2' to keep things the "
"way they are or you can switch to the new behavior right away "
"by setting `Meta.manager_inheritance_from_future` to `True`.",
)
self.assertIs(MyModel2.objects, MyModel2._default_manager)
# When there is a local manager we shouldn't get any warning
# and 'objects' shouldn't be created.
class MyModel3(ConcreteParentWithManager):
default = models.Manager()
self.assertIs(MyModel3.default, MyModel3._default_manager)
self.assertIsNone(getattr(MyModel3, 'objects', None))
# When there is an inherited manager we shouldn't get any warning
# and 'objects' shouldn't be created.
class MyModel4(AbstractParent, ConcreteParentWithManager):
pass
self.assertIs(MyModel4.default, MyModel4._default_manager)
self.assertIsNone(getattr(MyModel4, 'objects', None))
# With `manager_inheritance_from_future = True` 'objects'
# shouldn't be created.
class MyModel5(ConcreteParentWithManager):
class Meta:
manager_inheritance_from_future = True
self.assertIs(MyModel5.default, MyModel5._default_manager)
self.assertIsNone(getattr(MyModel5, 'objects', None))
def test_legacy_default_manager_promotion(self):
class ConcreteParent(models.Model):
concrete = models.Manager()
class AbstractParent(models.Model):
abstract = models.Manager()
class Meta:
abstract = True
with warnings.catch_warnings(record=True) as warns:
warnings.simplefilter('always', RemovedInDjango20Warning)
class MyModel(ConcreteParent, AbstractParent):
pass
self.assertEqual(len(warns), 1)
self.assertEqual(
str(warns[0].message),
"Managers from concrete parents will soon qualify as default "
"managers if they appear before any other managers in the "
"MRO. As a result, 'abstract' declared on "
"'managers_regress.AbstractParent' will no longer be the "
"default manager for 'managers_regress.MyModel' in favor of "
"'concrete' declared on 'managers_regress.ConcreteParent'. "
"You can redeclare 'abstract' on 'MyModel' to keep things the "
"way they are or you can switch to the new behavior right "
"away by setting `Meta.manager_inheritance_from_future` to "
"`True`.",
)
self.assertIs(MyModel.abstract, MyModel._default_manager)
class MyModel2(ConcreteParent, AbstractParent):
abstract = models.Manager()
self.assertIs(MyModel2.abstract, MyModel2._default_manager)
class MyModel3(ConcreteParent, AbstractParent):
class Meta:
manager_inheritance_from_future = True
self.assertIs(MyModel3.concrete, MyModel3._default_manager)

13
tests/many_to_one/tests.py
View File

@ -4,7 +4,7 @@ from copy import deepcopy
from django.core.exceptions import FieldError, MultipleObjectsReturned
from django.db import models, transaction
from django.db.utils import IntegrityError
from django.test import TestCase
from django.test import TestCase, ignore_warnings
from django.utils import six
from django.utils.deprecation import RemovedInDjango20Warning
from django.utils.translation import ugettext_lazy
@ -580,6 +580,7 @@ class ManyToOneTests(TestCase):
with self.assertNumQueries(1):
self.assertEqual(th.child_set.count(), 0)
@ignore_warnings(category=RemovedInDjango20Warning) # for use_for_related_fields deprecation
def test_related_object(self):
public_school = School.objects.create(is_public=True)
public_student = Student.objects.create(school=public_school)
@ -608,6 +609,16 @@ class ManyToOneTests(TestCase):
finally:
School._default_manager.use_for_related_fields = False
School._meta.base_manager_name = 'objects'
School._meta._expire_cache()
try:
private_student = Student.objects.get(pk=private_student.pk)
with self.assertRaises(School.DoesNotExist):
private_student.school
finally:
School._meta.base_manager_name = None
School._meta._expire_cache()
def test_hasattr_related_object(self):
# The exception raised on attribute access when a related object
# doesn't exist should be an instance of a subclass of `AttributeError`

24
tests/one_to_one/tests.py
View File

@ -1,7 +1,8 @@
from __future__ import unicode_literals
from django.db import IntegrityError, connection, transaction
from django.test import TestCase
from django.test import TestCase, ignore_warnings
from django.utils.deprecation import RemovedInDjango20Warning
from .models import (
Bar, Director, Favorites, HiddenPointer, ManualPrimaryKey, MultiModel,
@ -422,6 +423,7 @@ class OneToOneTests(TestCase):
hasattr(Target, HiddenPointer._meta.get_field('target').remote_field.get_accessor_name())
)
@ignore_warnings(category=RemovedInDjango20Warning) # for use_for_related_fields deprecation
def test_related_object(self):
public_school = School.objects.create(is_public=True)
public_director = Director.objects.create(school=public_school, is_temp=False)
@ -473,6 +475,26 @@ class OneToOneTests(TestCase):
finally:
Director._default_manager.use_for_related_fields = False
School._meta.base_manager_name = 'objects'
School._meta._expire_cache()
try:
private_director = Director._base_manager.get(pk=private_director.pk)
with self.assertRaises(School.DoesNotExist):
private_director.school
finally:
School._meta.base_manager_name = None
School._meta._expire_cache()
Director._meta.base_manager_name = 'objects'
Director._meta._expire_cache()
try:
private_school = School._base_manager.get(pk=private_school.pk)
with self.assertRaises(Director.DoesNotExist):
private_school.director
finally:
Director._meta.base_manager_name = None
Director._meta._expire_cache()
def test_hasattr_related_object(self):
# The exception raised on attribute access when a related object
# doesn't exist should be an instance of a subclass of `AttributeError`

4
tests/proxy_models/models.py
View File

@ -85,6 +85,8 @@ class StatusPerson(MyPerson):
"""
status = models.CharField(max_length=80)
objects = models.Manager()
# We can even have proxies of proxies (and subclass of those).
@ -96,6 +98,8 @@ class MyPersonProxy(MyPerson):
class LowerStatusPerson(MyPersonProxy):
status = models.CharField(max_length=80)
objects = models.Manager()
@python_2_unicode_compatible
class User(models.Model):